Two Receptor-Like Genes, Vfa1 and Vfa2, Confer Resistance to the Fungal Pathogen Venturia inaequalis Inciting Apple Scab Disease

• Published in: Molecular plant-microbe interactions Vol. 21; no. 4; pp. 448 - 458
• Main Authors: Malnoy, M, Xu, M, Borejsza-Wysocka, E, Korban, S.S, Aldwinckle, H.S
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.04.2008; The American Phytopathological Society
• Subjects: Agrobacterium tumefaciens - genetics; apples; Ascomycota - growth & development; Bacterial plant pathogens; Biological and medical sciences; Blotting, Southern; Blotting, Western; disease resistance; DNA, Bacterial - genetics; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; genes; genetic resistance; genetic transformation; Immunity, Innate - genetics; loci; Malus; Malus domestica; Malus floribunda; Models, Genetic; nursery crops; ornamental woody plants; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Proteins - physiology; Ploidies; Polymerase Chain Reaction; receptor-like genes; receptors; Rosaceae - genetics; Rosaceae - microbiology; scab diseases; Southern blotting; Transformation, Genetic; transgenic plants; Venturia inaequalis; Vf gene; Plant pathogen; Microbiology; Rosaceae; Fungi; Plant; Agrobacterium; Gene; Dicotyledones; Blotting assay; Angiospermae; Immunoblotting assay; Bacteria; Southern blotting; Vector; Gram negative bacteria; Ascomycota; Venturia inaequalis; Broadleaved ornamental tree; Transposable element; IS element; Polymerase chain reaction; Resistance; Spermatophyta; Rhizobiaceae; Vf gene; Cultivar
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-21-4-0448

The Vf locus, originating from the crabapple species Malus floribunda 821, confers resistance to five races of the fungal pathogen Venturia inaequalis, the causal agent of apple scab disease. Previously, a cluster of four receptor-like genes, Vfa1, Vfa2, Vfa3, and Vfa4, was identified within the Vf locus. Because the amino-acid sequence of Vfa3 is truncated, it was deemed nonfunctional. In this study, each of the three full-length Vfa genes was introduced into a plant cloning vector, pCAMBIA2301, and used for Agrobacterium-mediated transformation of two apple cultivars, Galaxy and McIntosh, to assess functionality of these genes and to characterize their roles in resistance to V. inaequalis. Transformed apple lines carrying each of Vfa1, Vfa2, or Vfa4 were developed, analyzed for the presence of the transgene using polymerase chain reaction and Southern blotting, and assayed for resistance to apple scab following inoculation with V. inaequalis. Transformed lines expressing Vfa4 were found to be susceptible to apple scab, whereas those expressing either Vfa1 or Vfa2 exhibited partial resistance to apple scab. Based on Western blot analysis as well as microscopic analysis of plant resistance reactions, the roles of Vfa1 and Vfa2 in apple scab disease resistance response are discussed.